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/****************************************************************************
** File: icmp.c
**
** Author: Mike Borella
**
** Comments: Dump ICMP header information
**
*****************************************************************************/
#include "config.h"
#include <stdio.h>
#include "ip_icmp.h"
/* rfc1191 */
struct mtu_discovery
{
short unused;
short nexthopmtu;
};
struct tok
{
int v; /* value */
char *s; /* string */
};
static struct tok icmp2str[] =
{
{ ICMP_ECHOREPLY, "echo reply" },
{ ICMP_SOURCEQUENCH, "source quench" },
{ ICMP_ECHO, "echo request" },
{ ICMP_ROUTERSOLICIT, "router solicitation" },
{ ICMP_TSTAMP, "time stamp request" },
{ ICMP_TSTAMPREPLY, "time stamp reply" },
{ ICMP_IREQ, "information request" },
{ ICMP_IREQREPLY, "information reply" },
{ ICMP_MASKREQ, "address mask request" },
{ 0, NULL }
};
extern u_char *packet_end;
/*----------------------------------------------------------------------------
**
** dump_icmp()
**
** Parse ICMP header and dump fields
**
**----------------------------------------------------------------------------
*/
void dump_icmp(u_char *bp, u_char *bp2)
{
char *cp;
struct icmp *dp;
struct ip *ip;
char *str, *fmt;
struct ip *oip;
struct udphdr *ouh;
u_int hlen, dport, mtu;
char buf[256];
dp = (struct icmp *)bp;
ip = (struct ip *) bp2;
str = buf;
printf("----------------------------------------------------------\n");
printf(" ICMP Header\n");
printf("----------------------------------------------------------\n");
printf("Type: %d ", dp->icmp_type);
switch (dp->icmp_type)
{
case ICMP_UNREACH:
printf("(unreachable)\n");
printf("Code: %d ", dp->icmp_code);
switch (dp->icmp_code)
{
case ICMP_UNREACH_PROTOCOL:
printf("(protocol)\n");
printf("Destination IP: %s\n");
break;
case ICMP_UNREACH_PORT:
printf("(port)\n");
printf("Destination IP: %s\n");
oip = &dp->icmp_ip;
hlen = oip->ip_hl * 4;
ouh = (struct udphdr *)(((u_char *)oip) + hlen);
dport = ntohs(ouh->dest);
switch (oip->ip_p)
{
case IPPROTO_TCP:
printf("tcp port %s unreachable\n", tcpport_string(dport));
break;
case IPPROTO_UDP:
printf("udp port %s unreachable\n", udpport_string(dport));
break;
default:
printf("Unknown protocol\n");
break;
}
break;
case ICMP_UNREACH_NEEDFRAG:
{
struct mtu_discovery *mp;
mp = (struct mtu_discovery *)&dp->icmp_void;
mtu = EXTRACT_16BITS(&mp->nexthopmtu);
printf("(fragmentation needed)\n");
printf("Destination IP: %s\n");
if (mtu) printf("MTU = %d\n", mtu);
}
break;
default:
printf("(unknown)\n");
break;
}
break;
case ICMP_TIMXCEED:
switch (dp->icmp_code)
{
case ICMP_TIMXCEED_INTRANS:
printf("(time exceeded in transit)\n");
break;
case ICMP_TIMXCEED_REASS:
printf("(time exceeded for IP reassembly)\n");
break;
default:
printf("Time exceeded-#%d", dp->icmp_code);
break;
}
break;
default:
str = tok2str(icmp2str, "type-#%d", dp->icmp_type);
break;
}
printf("icmp: %s", str);
return;
}
/*
* Convert a token value to a string; use "fmt" if not found.
*/
const char *tok2str(register const struct tok *lp, register const char *fmt,
register int v)
{
static char buf[128];
while (lp->s != NULL)
{
if (lp->v == v) return (lp->s);
++lp;
}
if (fmt == NULL) fmt = "#%d";
sprintf(buf, fmt, v);
return (buf);
}
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